Canada and Mexico agreed Thursday to US President-elect Donald Trump's demand to have a fresh look at their tripartite 22-year-old free trade pact, fearing they could be shut out of the US market.

But the two US allies diverged on the level of changes to the North American Free Trade Agreement (NAFTA) each was willing to accept, with Mexico taking a harder line.

The 1994 trade pact became a source of friction with America's neighbors during the campaign when Trump called NAFTA the worst trade deal the United States has ever signed.

The Republican president-elect's protectionist notions to repatriate American jobs lost to free trade sent shockwaves through Canada and Mexico's economies, which both rely heavily on exports to the United States.